/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;

using ZXing.Common;

namespace ZXing.Datamatrix.Internal
{
   /// <summary>
   /// <author>bbrown@google.com (Brian Brown)</author>
   /// </summary>
   sealed class BitMatrixParser
   {
      private readonly BitMatrix mappingBitMatrix;
      private readonly BitMatrix readMappingMatrix;
      private readonly Version version;

      /// <summary>
      /// <param name="bitMatrix"><see cref="BitMatrix" />to parse</param>
      /// <exception cref="FormatException">if dimension is <8 or>144 or not 0 mod 2</exception>
      /// </summary>
      internal BitMatrixParser(BitMatrix bitMatrix)
      {
         int dimension = bitMatrix.Height;
         if (dimension < 8 || dimension > 144 || (dimension & 0x01) != 0)
         {
            return;
         }

         version = readVersion(bitMatrix);
         if (version != null)
         {
            mappingBitMatrix = extractDataRegion(bitMatrix);
            readMappingMatrix = new BitMatrix(mappingBitMatrix.Width, mappingBitMatrix.Height);
         }
      }

      public Version Version
      {
         get { return version; }
      }

      /// <summary>
      /// <p>Creates the version object based on the dimension of the original bit matrix from 
      /// the datamatrix code.</p>
      ///
      /// <p>See ISO 16022:2006 Table 7 - ECC 200 symbol attributes</p>
      /// 
      /// <param name="bitMatrix">Original <see cref="BitMatrix" />including alignment patterns</param>
      /// <returns><see cref="Version" />encapsulating the Data Matrix Code's "version"</returns>
      /// <exception cref="FormatException">if the dimensions of the mapping matrix are not valid</exception>
      /// Data Matrix dimensions.
      /// </summary>
      internal static Version readVersion(BitMatrix bitMatrix)
      {
         int numRows = bitMatrix.Height;
         int numColumns = bitMatrix.Width;
         return Version.getVersionForDimensions(numRows, numColumns);
      }

      /// <summary>
      /// <p>Reads the bits in the <see cref="BitMatrix" />representing the mapping matrix (No alignment patterns)
      /// in the correct order in order to reconstitute the codewords bytes contained within the
      /// Data Matrix Code.</p>
      ///
      /// <returns>bytes encoded within the Data Matrix Code</returns>
      /// <exception cref="FormatException">if the exact number of bytes expected is not read</exception>
      /// </summary>
      internal byte[] readCodewords()
      {
         byte[] result = new byte[version.getTotalCodewords()];
         int resultOffset = 0;

         int row = 4;
         int column = 0;

         int numRows = mappingBitMatrix.Height;
         int numColumns = mappingBitMatrix.Width;

         bool corner1Read = false;
         bool corner2Read = false;
         bool corner3Read = false;
         bool corner4Read = false;

         // Read all of the codewords
         do
         {
            // Check the four corner cases
            if ((row == numRows) && (column == 0) && !corner1Read)
            {
               result[resultOffset++] = (byte)readCorner1(numRows, numColumns);
               row -= 2;
               column += 2;
               corner1Read = true;
            }
            else if ((row == numRows - 2) && (column == 0) && ((numColumns & 0x03) != 0) && !corner2Read)
            {
               result[resultOffset++] = (byte)readCorner2(numRows, numColumns);
               row -= 2;
               column += 2;
               corner2Read = true;
            }
            else if ((row == numRows + 4) && (column == 2) && ((numColumns & 0x07) == 0) && !corner3Read)
            {
               result[resultOffset++] = (byte)readCorner3(numRows, numColumns);
               row -= 2;
               column += 2;
               corner3Read = true;
            }
            else if ((row == numRows - 2) && (column == 0) && ((numColumns & 0x07) == 4) && !corner4Read)
            {
               result[resultOffset++] = (byte)readCorner4(numRows, numColumns);
               row -= 2;
               column += 2;
               corner4Read = true;
            }
            else
            {
               // Sweep upward diagonally to the right
               do
               {
                  if ((row < numRows) && (column >= 0) && !readMappingMatrix[column, row])
                  {
                     result[resultOffset++] = (byte)readUtah(row, column, numRows, numColumns);
                  }
                  row -= 2;
                  column += 2;
               } while ((row >= 0) && (column < numColumns));
               row += 1;
               column += 3;

               // Sweep downward diagonally to the left
               do
               {
                  if ((row >= 0) && (column < numColumns) && !readMappingMatrix[column, row])
                  {
                     result[resultOffset++] = (byte)readUtah(row, column, numRows, numColumns);
                  }
                  row += 2;
                  column -= 2;
               } while ((row < numRows) && (column >= 0));
               row += 3;
               column += 1;
            }
         } while ((row < numRows) || (column < numColumns));

         if (resultOffset != version.getTotalCodewords())
         {
            return null;
         }
         return result;
      }

      /// <summary>
      /// <p>Reads a bit of the mapping matrix accounting for boundary wrapping.</p>
      /// 
      /// <param name="row">Row to read in the mapping matrix</param>
      /// <param name="column">Column to read in the mapping matrix</param>
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>value of the given bit in the mapping matrix</returns>
      /// </summary>
      bool readModule(int row, int column, int numRows, int numColumns)
      {
         // Adjust the row and column indices based on boundary wrapping
         if (row < 0)
         {
            row += numRows;
            column += 4 - ((numRows + 4) & 0x07);
         }
         if (column < 0)
         {
            column += numColumns;
            row += 4 - ((numColumns + 4) & 0x07);
         }
         readMappingMatrix[column, row] = true;
         return mappingBitMatrix[column, row];
      }

      /// <summary>
      /// <p>Reads the 8 bits of the standard Utah-shaped pattern.</p>
      /// 
      /// <p>See ISO 16022:2006, 5.8.1 Figure 6</p>
      /// 
      /// <param name="row">Current row in the mapping matrix, anchored at the 8th bit (LSB) of the pattern</param>
      /// <param name="column">Current column in the mapping matrix, anchored at the 8th bit (LSB) of the pattern</param>
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>byte from the utah shape</returns>
      /// </summary>
      int readUtah(int row, int column, int numRows, int numColumns)
      {
         int currentByte = 0;
         if (readModule(row - 2, column - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row - 2, column - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row - 1, column - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row - 1, column - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row - 1, column, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row, column - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row, column - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(row, column, numRows, numColumns))
         {
            currentByte |= 1;
         }
         return currentByte;
      }

      /// <summary>
      /// <p>Reads the 8 bits of the special corner condition 1.</p>
      /// 
      /// <p>See ISO 16022:2006, Figure F.3</p>
      /// 
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>byte from the Corner condition 1</returns>
      /// </summary>
      int readCorner1(int numRows, int numColumns)
      {
         int currentByte = 0;
         if (readModule(numRows - 1, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 1, 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 1, 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(2, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(3, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         return currentByte;
      }

      /// <summary>
      /// <p>Reads the 8 bits of the special corner condition 2.</p>
      /// 
      /// <p>See ISO 16022:2006, Figure F.4</p>
      /// 
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>byte from the Corner condition 2</returns>
      /// </summary>
      int readCorner2(int numRows, int numColumns)
      {
         int currentByte = 0;
         if (readModule(numRows - 3, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 2, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 1, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 4, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 3, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         return currentByte;
      }

      /// <summary>
      /// <p>Reads the 8 bits of the special corner condition 3.</p>
      /// 
      /// <p>See ISO 16022:2006, Figure F.5</p>
      /// 
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>byte from the Corner condition 3</returns>
      /// </summary>
      int readCorner3(int numRows, int numColumns)
      {
         int currentByte = 0;
         if (readModule(numRows - 1, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 1, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 3, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 3, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         return currentByte;
      }

      /// <summary>
      /// <p>Reads the 8 bits of the special corner condition 4.</p>
      /// 
      /// <p>See ISO 16022:2006, Figure F.6</p>
      /// 
      /// <param name="numRows">Number of rows in the mapping matrix</param>
      /// <param name="numColumns">Number of columns in the mapping matrix</param>
      /// <returns>byte from the Corner condition 4</returns>
      /// </summary>
      int readCorner4(int numRows, int numColumns)
      {
         int currentByte = 0;
         if (readModule(numRows - 3, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 2, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(numRows - 1, 0, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 2, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(0, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(1, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(2, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         currentByte <<= 1;
         if (readModule(3, numColumns - 1, numRows, numColumns))
         {
            currentByte |= 1;
         }
         return currentByte;
      }

      /// <summary>
      /// <p>Extracts the data region from a <see cref="BitMatrix" />that contains
      /// alignment patterns.</p>
      /// 
      /// <param name="bitMatrix">Original <see cref="BitMatrix" />with alignment patterns</param>
      /// <returns>BitMatrix that has the alignment patterns removed</returns>
      /// </summary>
      BitMatrix extractDataRegion(BitMatrix bitMatrix)
      {
         int symbolSizeRows = version.getSymbolSizeRows();
         int symbolSizeColumns = version.getSymbolSizeColumns();

         if (bitMatrix.Height != symbolSizeRows)
         {
            throw new ArgumentException("Dimension of bitMarix must match the version size");
         }

         int dataRegionSizeRows = version.getDataRegionSizeRows();
         int dataRegionSizeColumns = version.getDataRegionSizeColumns();

         int numDataRegionsRow = symbolSizeRows / dataRegionSizeRows;
         int numDataRegionsColumn = symbolSizeColumns / dataRegionSizeColumns;

         int sizeDataRegionRow = numDataRegionsRow * dataRegionSizeRows;
         int sizeDataRegionColumn = numDataRegionsColumn * dataRegionSizeColumns;

         BitMatrix bitMatrixWithoutAlignment = new BitMatrix(sizeDataRegionColumn, sizeDataRegionRow);
         for (int dataRegionRow = 0; dataRegionRow < numDataRegionsRow; ++dataRegionRow)
         {
            int dataRegionRowOffset = dataRegionRow * dataRegionSizeRows;
            for (int dataRegionColumn = 0; dataRegionColumn < numDataRegionsColumn; ++dataRegionColumn)
            {
               int dataRegionColumnOffset = dataRegionColumn * dataRegionSizeColumns;
               for (int i = 0; i < dataRegionSizeRows; ++i)
               {
                  int readRowOffset = dataRegionRow * (dataRegionSizeRows + 2) + 1 + i;
                  int writeRowOffset = dataRegionRowOffset + i;
                  for (int j = 0; j < dataRegionSizeColumns; ++j)
                  {
                     int readColumnOffset = dataRegionColumn * (dataRegionSizeColumns + 2) + 1 + j;
                     if (bitMatrix[readColumnOffset, readRowOffset])
                     {
                        int writeColumnOffset = dataRegionColumnOffset + j;
                        bitMatrixWithoutAlignment[writeColumnOffset, writeRowOffset] = true;
                     }
                  }
               }
            }
         }
         return bitMatrixWithoutAlignment;
      }

   }
}
